The present invention relates to an imaging apparatus that operates in both a right-side-up orientation and an upside-down orientation.
One imaging apparatus of this type is a ceiling-mounted video surveillance camera that swivels vertically back and forth to monitor an area extending in front of and behind the camera location. As the camera swivels from looking horizontally forward to looking diagonally forward, then vertically down, the picture displayed on the monitor screen changes from a right-side-up horizontal view to an oblique view, then a plan view. As the camera continues to swivel from looking vertically down to looking diagonally backward, then horizontally backward, if no corrective action is taken, the displayed picture appears first obliquely upside down, then completely upside down.
A conventional method of avoiding an upside-down picture is to rotate the camera one hundred eighty degrees (180xc2x0) about its optic axis each time the camera passes through the vertical-down orientation. FIG. 1 shows a simple block diagram of a conventional imaging apparatus, comprising a control unit 210, a video camera 300, a rotating mount 310, and a swiveling mount 320, in which this method is adopted. The control unit 210 controls the rotating mount 310, which rotates the video camera 300 about its optic axis. The control unit 210 also controls the swiveling mount 320, which swivels the video camera 300 and rotating mount 310 about an axis perpendicular to the optic axis of the video camera 300.
A problem is that when the camera is physically rotated about its optic axis, to a person watching the picture on the monitor screen, the scene being viewed appears to rotate in a dizzying manner. A further problem is that the rotating mount 310 is bulky and expensive.
An object of the present invention is to right an upside-down image produced by an imaging apparatus, without physically rotating the apparatus.
Another object of the invention is to combine the image-righting function with other image-processing functions, such as noise reduction, slow shutter, frame save/recall, and zoom.
The invented image-processing method comprises the steps of storing a source image produced by an imaging device in a memory circuit, and reading the source image from the memory circuit to generate an output image. The source image data-are read from the memory circuit in one order if the source image is right-side up, and in a vertically reverse order, or a vertically and horizontally reverse order, if the source image is upside down. The output image is therefore always right-side up.
The image-righting function is combined with image-processing functions such as noise reduction and slow shutter by reading the source image from the memory circuit again to generate an internal image, which is always read as if the source image were right-side-up order. The image-righting function is combined with the save/recall function by leaving the source image stored in the memory circuit for later recall. The image-righting function is combined with the zoom function by omitting parts of the source image when the source image is read from the memory circuit.
The invention also provides an image-processing apparatus that operates in different orientations and employs the invented image-processing method to right upside-down images.